This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to find out whether Minocycline will be a safe and effective therapy to reduce loss of protein from the kidney (detected in the urine) in subjects with Type II Diabetes Mellitus and diabetic kidney disease who are already taking high blood pressure medications such as Angiotensin-Converting Enzyme inhibitors (ACE inhibitiors) and angiotensin II blockers (ARBs) to help prevent or slow the progression (worsening) of diabetic kidney disease. This study will use a prospective, single center, randomized, placebo-control design. A total of 130 subjects with Diabetic Nephropathy will be enrolled. Subjects will be randomized based on the mean 24 hour urine protein levels at baseline, as follows: (a) <3g/24h and (b) >= 3g/24h. The study will consist of a 3-week screening period, a baseline visit during which the subjects will be randomly assigned to the active drug (Minocycline 100 mg PO BID) or to matching placebo, a 24-week treatment period, a study completion visit at week 24, and a 2-month post-completion washout period with repeat urine and blood measures. This study will last 35 weeks.